Significant Accounting Policies - Narrative (Details) people in Millions, patient in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021 USD ($) patient people state location clinic	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) patient Segment people state location clinic	Jun. 30, 2020 USD ($)
Significant Accounting Policies [Line Items]
Number of pharmacy plan members | people	108		108
Number of patients served per year | patient	1		1
Number of reportable segments | Segment			4
Health insurer fee	$ 0	$ 248,000,000	$ 0	$ 519,000,000
Related party transaction, expenses from transactions with related party	10,000,000	3,000,000	19,000,000	23,000,000
Related party transaction, other revenues from transactions with related party	$ 19,000,000	$ 22,000,000	$ 37,000,000	$ 43,000,000
Heartland Healthcare Services
Significant Accounting Policies [Line Items]
Number of states in which entity operates | state	4		4
Retail/ LTC
Significant Accounting Policies [Line Items]
Number of stores | location	9,900		9,900
Number of walk in medical clinics | clinic	1,100		1,100
Health Care Benefits
Significant Accounting Policies [Line Items]
Number of people served | people	34		34